This invention relates to a machine for forming vertical stacks of plates from a stream of plates transported horizontally on a conveyor in a shingled fashion.
The plates used in storage batteries are formed by placing a lead oxide paste on a cast grid. The plates are then flash dried to remove moisture from the paste and cause it to set up. This process is accomplished in a pasted plate machine which is standard in the industry. All of the moisture is not removed from the plates during flash drying, however, and thus the plates that are discharged from the plate machine are not completely rigid and are somewhat tacky. The plates exit the machine on an output conveyor at a high rate of speed which makes them difficult to handle and form into the horizontal stacks which are used in the remainder in the battery construction process.
Traditionally, the plates have been deposited onto a slower speed conveyor and then removed from the slower conveyor and formed into stacks by hand. Due to its lower speed, the plates are deposited on the slower conveyor in an overlapping shingled fashion. Thus, they can be removed simply by stopping movement of the first plate with one hand which causes the plates to bunch together so that a group of the plates can be lifted off of the conveyor and formed into a stack. Since the stacks are quite heavy and the machines create a hot dusty environment, this is a difficult job and it is desirable to automate the stacking process.
In other industries plates that are provided in a shingled fashion are stacked by interrupting the movement of the first plate, thereby causing the plates to stand up on end and form a horizontal stack which can be removed with a clamping mechanism. However, freshly made battery plates are not slippery enough or stiff enough to form stacks in this manner.
Prior art machines have been provided to stack plates from a pasted plate machine. However, the difficulty in causing a pause between plates in a shingled stream of plates, as is necessary for removal of the stacks, has caused these machines to handle plates moving at the high output speed of the plate machine, or even increase their speed to form a separation between plates. Prior art stackers of this type are manufactured by Wirtz Manufacturing Co., Inc. of Port Huron, Mich. and Uranio SpA, Sovema Division via Torricelli of Verona, Italy. These prior art devices have been able to form stacks by diverting plates or temporarily supporting plates to create a pause between stacks. However, due to the high speed involved, slight variations in the timing of the arrival of plates at the diversion device cause the diversion to often be too early or too late. As a result errors occur which make the machines unreliable. In addition, the high speed sorting makes the machines extremely expensive. Accordingly, hand stacking remains the norm.
The subject invention overcomes the shortcomings of the prior art by forming vertical stacks of plates from a shingled stream by merely allowing the plates to drop off at the discharge end of the slower speed conveyor they are being carried on onto a second conveyor that is not moving until a stack is formed on the second conveyor. Each completed stack is then removed by moving the second conveyor after the last plate is deposited on the stack. The stream of plates is prevented from moving with the first conveyor when the second conveyor is being moved in order to create the necessary pause between stacks. This preferably is accomplished by squeezing the plates between the jaws of a clamp mechanism Because clamping is equally effective over the entire length of a plate, slight variations in timing of the plates does not create a problem, particularly when the plates are traveling on a slower speed conveyor when the clamping occurs.
In a preferred embodiment, a raisable gate located across the second conveyor engages the plates as they fall from the first conveyor and causes the stacks to be straight. Also in the preferred embodiment, a controller activates the clamp when the proper number of plates has passed the clamp. After a sufficient time for the plates downstream of the clamp to be discharged and complete the stack, the controller raises the gate and starts the second conveyor moving. After the stack has been moved out of the way the controller stops the second conveyor, lowers the gate and releases the clamp and another stack is formed. The controller can be annunciated by a counter that counts the plates on the second conveyor or by a sensor that measures the height of the stack.
Since plate making machines typically produce plates in side-by-side pairs, two side-by-side second conveyors are provided. If it is desired to align the plates transversely on the conveyors before they are displaced onto a stack, the conveyors can diverge from one another in order to allow an alignment machine to be placed on each side of both conveyors.
Accordingly, it is a principal object of the subject invention to provide a method for forming a vertical stack of plates from a shingled stream of horizontally oriented plates.
It is a further object of the present invention to also provide a disruption in the flow of the plates while a completed stack is being moved from the spot where it is formed.
It is a still further object of the subject invention to provide an apparatus for practicing the foregoing method.
It is a further object of the subject invention to provide such an apparatus which is not affected by variations in the timing of the plates.
It is a yet further object of the present invention to provide such an apparatus that clamps the plates to disrupt their flow.
It is a further object of the subject invention to provide such an apparatus that causes side-by-side pairs of plates from the plate making machine to be separated from one another before they are formed into stacks to facilitate lateral alignment of the plates.
The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.